Rats and mosquitoes in Orange County: free help from OC Vector Control

What does OC Vector Control do?

It is a public district, formed in 1947 as the Orange County Mosquito Abatement District, that serves county residents. Its board has one member from each of 34 cities plus one for the county (about the district). Its service list covers four pests at a home:

• Mosquitoes: if needed, an inspector checks your property and the area around it for breeding water and explains how to keep it gone.
• Rats: an inspector looks for what draws them and how they get in.
• Red imported fire ants: an inspector confirms the mound and treats it; the colony can take up to a month to go inactive.
• Flies: an inspector looks for where they breed.

It also identifies insects you drop off or mail in, and sends treatment and disease alerts. Termites are not on the list; see our termites guide.

Will OC Vector Control help with roof rats?

Normally yes, with advice. The rat program is paused until after December 1, 2026, so check the Report an Issue page first. On a rat visit, the inspector walks the outside of the home and the yard and points out what is attracting rats and where they may be getting in. The guidance covers keeping rats out of the house and the control steps you can take yourself, and the district notes that removing the attractants may be all it takes.

Roof rats are slender, with a tail longer than the head and body. They travel along utility lines and fences and feed on birdseed, pet food and backyard fruit and nuts. Our roof rat how-to shows how to find and seal the gaps yourself, whatever the district's rat service status.

Why are mosquitoes biting me during the day?

Small black mosquitoes with white stripes that bite in daylight, even indoors, are the invasive Aedes mosquitoes. They lay eggs one at a time on the waterline of any container, from vases and plant saucers to buckets and bromeliads, and the eggs can stay alive for years. The district's advice:

• Dump and drain anything holding water at least once a week.
• Scrub bird baths and pet bowls weekly.
• Drill a hole in containers that keep collecting water.
• Use a repellent with DEET, picaridin, IR3535 or oil of lemon eucalyptus, and fix torn window screens.

If they keep coming, ask for the free inspection; mosquitoes fly over fences, so the inspector also checks nearby sources. In Mission Viejo, where Aedes aegypti are common, the district is testing the release of sterile males, which do not bite, and is tracking results through 2026.

How do I get free mosquitofish?

The district gives mosquitofish free to Orange County residents, for water on their own property only. There is no pickup: submit a service request or call, and an inspector checks the water and delivers the fish. State rules require a permit to put them in waters of the state.

How do I request service or call OC Vector Control?

Use the service request form on its Report an Issue page, or contact the office in Garden Grove at 714-971-2421 or 949-654-2421, or ocvcd@ocvector.org. It is open Monday to Thursday 7 a.m. to 4:30 p.m. and Friday 7 a.m. to 3:30 p.m., closed weekends. Every city is on the Orange County hub.

As of November 2026. The district's own pages have the final word on what it offers.